CDKN2A copy number and p16 expression in malignant pleural mesothelioma in relation to asbestos exposure

BMC Cancer

Table 2 Association of gender, age, histologic type, and exposure with p16 expression and CDKN2A copies in MPM

				All	Gender		Age^a		Mesothelioma (MPM) histologic types			Asbestos exposure, all MPM histologic types^b		Very high vs. low exposure, all MPM histologic types^b		Asbestos exposure, epithelioid histology
					Male	Female	<Median 62.5y	≥Median 62.5y	Epith.	Biphasic	Sarcom.	High^c	Low^d	Very high^e	Low^d	High^c	Low^d
			n^f	92	74	18	46	46	63	13	16	53	22	33	22	43	11
p16 staining by IHC	MPM tumor cells	neg	n (%)	50 (73)	42 (75)	8 (62)	24 (71)	26 (74)	37 (73)	7 (100)	6 (55)	34 (81)	10 (67)	21 (81)	10 (67)	30 (81)	4 (50)
	MPM tumor cells	pos	n (%)	19 (27)	14 (25)	5 (38)	10 (29)	9 (26)	14 (27)	0 (0)	5 (45)	8 (19)	5 (33)	5 (19)	5 (33)	7 (19)	4 (50)
	p				0.491^g		0.729^h		0.107^g			0.294^g		0.453^g		0.085^g
	MPM stromal cells	neg	n (%)	30 (53)	23 (51)	7 (58)	15 (52)	15 (54)	25 (51)	5 (63)	–	18 (49)	10 (83)	10 (42)	10 (83)	18 (51)	6 (75)
	MPM stromal cells	pos	n (%)	27 (47)	22 (49)	5 (42)	14 (48)	13 (46)	24 (49)	3 (37)	–	19 (51)	2 (17)	14 (58)	2 (17)	17 (49)	2 (25)
	p				0.655^h		0.888^h		0.709^g			0.035*^h		0.018*^h		0.270^g
CDKN2A copy number by FISH	MPM tumor cells	abnormⁱ	n (%)	53 (84)	45 (90)	8 (62)	27 (90)	26 (79)	40 (89)	6 (75)	7 (70)	34 (94)	10 (71)	21 (96)	10 (71)	31 (97)	4 (57)
	MPM tumor cells	norm	n (%)	10 (16)	5 (10)	5 (38)	3 (10)	7 (21)	5 (11)	2 (25)	3 (30)	2 (6)	4 (29)	1 (4)	4 (29)	1 (3)	3 (43)
	p				0.025*^g		0.308^g		0.170^g			0.044*^g		0.064^g		0.014*^g

Association of gender, age, histologic type, and exposure with p16 expression and CDKN2A copy number status in malignant pleural mesothelioma (MPM)
^aAge at time of asbestos-analysis (i.e. surgery or autopsy); ^bFor stromal p16 staining analysis, sarcomatoid cases were excluded; ^cPulmonary asbestos fiber count ≥1.0 × 10⁶ fibres per gram dry lung; ^dPulmonary asbestos fiber count 0–0.5 × 10⁶ fibres per gram dry lung; ^ePulmonary asbestos fiber count ≥5.0 × 10⁶ fibres per gram dry lung; ^fTotal number of studied cases; ^gFisher’s Exact test (two-tailed). Tested for negative/abnormal and positive/normal results between the sub-categories; ^hChi-Square. Tested for negative/abnormal and positive/normal results between the sub-categories; ⁱCDKN2A copy number was considered as abnormal if homozygous deletion was shown in > 20% of the cells or hemizygosity in > 20% of the cells, or monosomy of chromosome 9 in ≥50%;
MPM malignant pleural mesothelioma, IHC immunohistochemistry, FISH fluorescence in situ hybridization, y years, P-values ≤0.05 with *

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